46
The recommended limit for transferring isochronous image data is 1000q (quadlets) per
cycle or 4096 bytes (with 400 Mb/s of bandwidth).
The table shows that the camera has to send 2560 pixels or 2 lines of video per cycle
when using an F-201B camera in format 2 mode 2 (1280 x 960 pixels, 8 bits per pixel)
at 15 fps. The camera thus uses 64% of available bandwidth. If the frame rate is
reduced to 7.5 fps the camera needs only 32% of the bandwidth. This allows up to three
cameras with these settings to be operated on the same bus.
L
If the cameras are operated with an external trigger the maximum trigger frequency
may not exceed the highest frame rate, so preventing frames from being lost.
The frame rates in video modes 0 to 2 are specified and set by IIDC v. 1.3.
In video Format_7 this can be set dynamically by the parameters described below.
The following formula is used to calculate the highest frame rate in Format_7.
s
AoiHeight
s
AoiHeight
s
s
T
T
T
T
FPS
FPS
Scan
Dump
Black
eTrans
Ch
CCD
In
µ
µ
µ
µ
37
,
63
1
,
4
)
1236
(
1
,
4
15
37
,
63
2
1
1
arg
⋅
+
⋅
−
+
⋅
+
⋅
=
+
+
+
=
=
FPS=f(AoiHeight)
0,00
20,00
40,00
60,00
80,00
100,00
120,00
140,00
160,00
180,00
200,00
0
200
400
600
800
1000
1200
1400
AoiHeight
fp
s
FPS
AoiHeight
FPS
AoiHeight
FPS
1236 12,74
240
51,33
1200 13,09
120
80,85
1024 15,16
60
113,48
960 16,09
30
142,17
600 24,50
15
162,74
480 29,67
-
-
Available bandwidth on the 1394 bus may limit the frame rate possible.